Lubricants



Patented Nov. 7, 1944 PATENT OFFICE LUBRICANTS I John H. Bannon, Union,N. J., assignor to Standard Oil Development Company, a corporation ofDelaware No Drawing. Application December 29, 1942,

Serial No. 470,451

11 Claims.

This invention relates to novel lubricants "and methods of preparing andusing same, and more particularly it relates to chemically inertlubricants, especially such which are suitable for use at lowtemperatures at least as low as atmospheric temperature or below.

According to the present invention zinc stearate, or other metal soap aswill be described later, is mixed with a liquid vehicle such as apetroleum distillate boiling above the naphtha boiling range, and highlyrefined so as to be substantially inert chemically, as may be obtainedby treating the petroleum distillate with oleum (fuming sulfuric acid)or by concentrated sulfuric acid under strong treating conditions, suchas by using a large amount of sulfuric acid or somewhat elevatedtemperatures, or both, or by treating with other chemical refiningagents, such as aluminum chloride.

These oils should be of the kerosene to lubricating oil boiling rangeand should have a viscosity of about 30-400 seconds Saybolt at 100 F.,and an A. S. T. M. pour point at least as low-as 40 F., and preferablybelow F., or lower, e. g. 40 F., 70" F. and even as low as 90 F., or

lower; Either a single petroleum distillate may be used or a mixture orblend of several different distillates, providing that either each oneseparately, or the mixture thereof, has been highly refined to theextent of making the oil substantially chemically inert.

Oils of the desired type, which are generally known as mineral whiteoils, are available on the market in various grades classified chieflyaccording to viscosity and-purity or inertness. For the purpose of thepresent invention it is preferredto use white oils which satisfy therequirements of the United States Pharmacopoeia, in other words,sufliciently chemically inert to permil; their use for medicinalpurposes as an internal lubricant. One such product which has beenavailable on the market for many years is sold under the trade nameNujol." The following is a list of additional U. S. P. oils with theirapproximate viscosity ranges:

Viscosity sec. Saybolt Univ. at 100 F.

U. S. P. white oils The product-called Nujol has a viscosity in thepurposes as an internal lubricant.

general viscosity of the Primol. Other oils of similar purity areavailable which have viscosities intermediate between those listedabove.

In addition to the above-mentioned U. S. P.

5 white oils, there are also a number of the white 0i1s marketedcommercially which are of a technical grade of purity, i. e., highlyrefined and substantially chemically inert, but not quite so absolutelyinert as to warrant use for medicinal ucts are available under thegeneral trade name Bayol and are available in various viscositiesranging from about 30-100 seconds? although generally sold to meetrelatively narrow viscosity l5 specifications, such as 30-35 seconds,50-55 seconds, 65-75 seconds, 80-90 seconds, 95-105 seconds, etc. Theabove-described white oils ordinarily have pour points ranging fromabout +35 F. down to 90 F., depending upon the source of the crudepetroleum from which they are derived, and, of course, depending to someextent upon the viscosity and boiling range of the particular distillatein question. For instance, a white oil made by treating a naphthenictype gas oil, and having a viscosity of about 35-40 seconds Saybolt at100 F., generally has a, pour point of -90 F. On the other hand Primol,which is a much higher boiling and higher viscosity fraction, generallyhas a pour point of F. Mar- 30 col having a viscosity of about 80-90seconds at 100 F. has a pour point of about 0 to +10 F.; and yet aproduct sold under the trade name Bayol F and having a viscosity ofabout 50-55 seconds Sayboltat 100 F., has a pour point of +35 F.Obviously for the purpose of the present invention these and othersimilar white oils may, if desired, be blended together to obtain anydesired combination of viscosity and pour point according to therequirements to which the lubricant will be applied in actual use. a

portion, or even practically all, of the hydrocarbon constituent of thelubricant may be removed due to contact with the hydrocarbons beingtreated in the equipment being lubricated. Although it has been foundthat zinc stearate is a very satisfactory soap for the purposes of thisinvention, magnesium stearate is also suitable, and calcium stearate isfairly satisfactory. It is/iireferred to use soaps of metals of group IIof the Mendeleefi Periodic Table. For instance, barium stearate may alsobe used. The acid radical of Such prodthe soap is preferably a fattyacid and preferably a saturated fatty acid which will not reactchemically with unsaturated hydrocarbons being treated in the equipmentbeing lubricated nor be subject to polymerization or condensation. dueto the presence of Friedel-Crafts catalysts. Instead of preparing thesoap from stearic acid, it may be made from synthetic acid made by theoxidation of paraffin wax-or from acids derived from the non-dryingvegetable or other fatty oils, or from fats. Mixtures of these variousmetal soaps may be used.

The proportions in which the two primary ingredients of the lubricantsof this invention are to be mixed, namely, the white oil and thelubricating metal soap, will depend to some extent on the type ofspecific constituents being used and on the purpose for which thelubricant will be used. For example, when the grease is to be used in agrease gun, the soap, e. g., zinc stearate, should comprise about 25-35%by weight of the total grease composition, whereas if the grease is tobe used in a grease cup, the amount of soapshould be somewhat higher,such as about 40-50 by weight. Generally the amount of the lubrieatingmetal soap to be used should be between the broader limits of about -60%by weight and the white oil about 40-90% by weight, the preferred limitsbeing about 20-50% by weight of soap and about 50-80 of white oil.

In carrying out this invention, the soap, such as zinc stearate, may bemixed directly into the mineral white oil to be used, or if desired, thereverse procedure may be used, namely, by gradually mixing or millingthe white oil into the zinc stearate. Although heating is not normallynecessary, the mixture may be heated, if desired. to a suitabletemperature, such as up to about 100 F, or 150 F. or so, in order totemporarily reduce the viscosity of the white oil to facilitate thedispersion of the soap therein.

In addition to the above two primary constituents, other addition agentsmay be used in minor amounts, such as dyes, anti-oxidants, pourdepressors, etc.

The lubricating greases of this invention are substantially chemicallyinert and are especially suitable for lubricating chemical processequipment such as processes involving the treatment of petroleumhydrocarbons, such as unsaturated gases or liquids with catalysts of theFriedel- Crafts type, e. g., aluminum chloride, boron fluoride, etc., orother catalysts, such a sulfuric acid. etc. The invention isparticularly suitable for use in conjunction with the manufacture ofsynthetic rubber, for instance, by lubricating bearings, stuffing boxes,valves, etc., with the substantially chemically inert lubricatinggreases of this invention. A particularly preferred method of usingthese greases is to impregnate an asbestos packing and then using theimpregnated packing for. lubrication of bearings, etc. Another verysatisfactory application of this invention is the use of this grease forlubricating plug valves or cocks which require a film of the lubricantbetween the valve and body, In the manufacture of certain types ofsynthetic rubbensuch as the one called butyl rubber, polymerizable, i.e., unsaturated, hydrocarbon gases such as isobutylene, butadiene. andisoprene. are treated at low temperature 1. e., below 40 F. andgenerally at'least as low as 70 F., e. g. 100 F. or even lower, with aFriedel-Crafts catalyst, especially aluminum chloride, dissolved in asolvent such" as methyl chloride or ethyl chloride, this operation beingordinarily carried out in the presence of a liquefied gaseoushydrocarbon such as ethylene, ethane, or even methane serving as adiluent and/ or refrigerant. In such a process difficulties have beenexperienced in obtaining satisfactory lubricants which are inert to theaction of the catalyst and unsaturated hydrocarbons used in the processand at the same time which will remain sufliciently plastic foraccomplishing the desired lubrication. The lubricating greases of thisinvention have been found to be very satisfactory for lubricating thevalves, bearings and other moving parts of the equipment used in such aprocess.

Generally the lubricating greases of this invention should have apenetration of at least 50 (according to the standard A. S. T. M,procedure at 77 F.) and should have a consistency of less than about1500 on the consistometer at 77 F. or a Saybolt viscosity of at leastabout 500 seconds at 77 F. In non-technical terms, the consistencyshould be approximately between that of a library paste and that of milkof magnesia, or very slightly thinner.

For the sake of illustration, the following specific examples are given:

Example 1 A Colombian gas oil was treated with fuming sulfuric acid, andafter removal of the acid sludge and washing the acid treated oil withwater and soda to remove the residual acid, the resultant mineral whiteoil had a viscosity of 37 seconds Saybolt at 100 F. and a pour point ofF. Similarly a higher boiling petroleum distillate of the lubricatingoil boiling range was treated with fuming sulfuric acid and afterremoval of acid sludge and washing, the resultant mineral white oil hada viscosity of about 340 seconds-Saybolt at F; and a pour point of 30 F.These two light and heavy mineral white oils were blended together insuitable proportions, about 2:1, to obtain a blend having a pour pointof about '70 F. It was then compounded with zinc stearate in theproportions of about 35% by weight of zinc stearate and 65% by weight ofthe White oil and the resultant grease was found very satisfactory forlubricating plug valves and other parts of equipment used in lowtemperature chemical processes.

Example 2 The procedure of Example 1 was repeated, except that a Winklergas oil was used instead of a Colombian gas oil as the petroleumdistillate from which the light mineral white oil was Prepared. Thefinished lubricating grease was likewise very satisfactory forlubrication of equipment used in the manufacture of butyl rubber.

Example 3 It is not intended that this invention be limited to thespecific materials which are recited merely for the sake ofillustration, but only by the appended claims in which it is intendedto/claim all novelty inherent in the invention as well as allmodifications coming within the scope and spirit of the invention.

low as atmospheric temperature.

2. Lubricant according to claim 1 in which the soap is a fatty acid soapof a metal of group II of the periodic table.

3. Lubricant according to claiml containing a saturated fatty acid soapof zinc.

4. Lubricant according to claim 1 containing at least 10-60% by Weightof zinc stearate. v

5. A lubricant comprising about 20-50% by weight of zinc stearate andabout 80-50% of a mineral white oil having a viscosity of about 30- 400seconds Saybolt at 100 F., said lubricant having a grease consistency attemperatures at least as low as atmospheric temperature.

6. Lubricant according to claim in which the white 011 has a pour pointbelow --50 F.

7. Lubricant according to claim 5 in which the white oil has a pourpoint below -50 F. and consists of a blend of low boiling white oilhaving a viscosityof about 30-40 seconds Saybolt and a pour point ofabout -90 F. and a high boiling white oil having a viscosity of about300-400 seconds Saybolt at 100 F. and. a pour point of about --30. a

8. A low temperature lubricant having a grease consistency comprisingessentially a mineral white oil of the kerosene to lubricating oilboiling range, having a viscosity of 30-400 seconds Sayboltat 100 F. anda pour point at least as low as -30 F and at least about of alubricating metal soap.

9. The method of lubricating chemical process machinery in which thelubricant comes in contact with active chemicals and in which thelubricant must remain plastic under the conditions of operation whichcomprises using as the lubricant therefor a chemically inert greaseconsisting essentially of about 40 to 90% of a mineral white oil havinga viscosity of about -400 seconds Saybolt at 100 F., and about 10-60% byweight of an inert lubricating metal soap.

10. The method of lubricating machinery used in the manufacture ofsynthetic rubber which comprises using as the lubricant therefor alubricating grease comprising essentially about by weight of a mineralwhite oil having a viscosity of about 30-400 seconds Saybolt at greasecontains about 20-50% of zinc stearate.

JOHN H. BANNON.

